/src/Google/Task/Runner.php
PHP | 284 lines | 149 code | 33 blank | 102 comment | 20 complexity | 13db5ea10d6adaf72758030726fcfc12 MD5 | raw file
- <?php
- /*
- * Copyright 2014 Google Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- /**
- * A task runner with exponential backoff support.
- *
- * @see https://developers.google.com/drive/web/handle-errors#implementing_exponential_backoff
- */
- class Google_Task_Runner
- {
- const TASK_RETRY_NEVER = 0;
- const TASK_RETRY_ONCE = 1;
- const TASK_RETRY_ALWAYS = -1;
- /**
- * @var integer $maxDelay The max time (in seconds) to wait before a retry.
- */
- private $maxDelay = 60;
- /**
- * @var integer $delay The previous delay from which the next is calculated.
- */
- private $delay = 1;
- /**
- * @var integer $factor The base number for the exponential back off.
- */
- private $factor = 2;
- /**
- * @var float $jitter A random number between -$jitter and $jitter will be
- * added to $factor on each iteration to allow for a better distribution of
- * retries.
- */
- private $jitter = 0.5;
- /**
- * @var integer $attempts The number of attempts that have been tried so far.
- */
- private $attempts = 0;
- /**
- * @var integer $maxAttempts The max number of attempts allowed.
- */
- private $maxAttempts = 1;
- /**
- * @var string $name The name of the current task (used for logging).
- */
- private $name;
- /**
- * @var callable $action The task to run and possibly retry.
- */
- private $action;
- /**
- * @var array $arguments The task arguments.
- */
- private $arguments;
- /**
- * @var array $retryMap Map of errors with retry counts.
- */
- protected $retryMap = [
- '500' => self::TASK_RETRY_ALWAYS,
- '503' => self::TASK_RETRY_ALWAYS,
- 'rateLimitExceeded' => self::TASK_RETRY_ALWAYS,
- 'userRateLimitExceeded' => self::TASK_RETRY_ALWAYS,
- 6 => self::TASK_RETRY_ALWAYS, // CURLE_COULDNT_RESOLVE_HOST
- 7 => self::TASK_RETRY_ALWAYS, // CURLE_COULDNT_CONNECT
- 28 => self::TASK_RETRY_ALWAYS, // CURLE_OPERATION_TIMEOUTED
- 35 => self::TASK_RETRY_ALWAYS, // CURLE_SSL_CONNECT_ERROR
- 52 => self::TASK_RETRY_ALWAYS // CURLE_GOT_NOTHING
- ];
- /**
- * Creates a new task runner with exponential backoff support.
- *
- * @param array $config The task runner config
- * @param string $name The name of the current task (used for logging)
- * @param callable $action The task to run and possibly retry
- * @param array $arguments The task arguments
- * @throws Google_Task_Exception when misconfigured
- */
- public function __construct(
- $config,
- $name,
- $action,
- array $arguments = array()
- ) {
- if (isset($config['initial_delay'])) {
- if ($config['initial_delay'] < 0) {
- throw new Google_Task_Exception(
- 'Task configuration `initial_delay` must not be negative.'
- );
- }
- $this->delay = $config['initial_delay'];
- }
- if (isset($config['max_delay'])) {
- if ($config['max_delay'] <= 0) {
- throw new Google_Task_Exception(
- 'Task configuration `max_delay` must be greater than 0.'
- );
- }
- $this->maxDelay = $config['max_delay'];
- }
- if (isset($config['factor'])) {
- if ($config['factor'] <= 0) {
- throw new Google_Task_Exception(
- 'Task configuration `factor` must be greater than 0.'
- );
- }
- $this->factor = $config['factor'];
- }
- if (isset($config['jitter'])) {
- if ($config['jitter'] <= 0) {
- throw new Google_Task_Exception(
- 'Task configuration `jitter` must be greater than 0.'
- );
- }
- $this->jitter = $config['jitter'];
- }
- if (isset($config['retries'])) {
- if ($config['retries'] < 0) {
- throw new Google_Task_Exception(
- 'Task configuration `retries` must not be negative.'
- );
- }
- $this->maxAttempts += $config['retries'];
- }
- if (!is_callable($action)) {
- throw new Google_Task_Exception(
- 'Task argument `$action` must be a valid callable.'
- );
- }
- $this->name = $name;
- $this->action = $action;
- $this->arguments = $arguments;
- }
- /**
- * Checks if a retry can be attempted.
- *
- * @return boolean
- */
- public function canAttempt()
- {
- return $this->attempts < $this->maxAttempts;
- }
- /**
- * Runs the task and (if applicable) automatically retries when errors occur.
- *
- * @return mixed
- * @throws Google_Task_Retryable on failure when no retries are available.
- */
- public function run()
- {
- while ($this->attempt()) {
- try {
- return call_user_func_array($this->action, $this->arguments);
- } catch (Google_Service_Exception $exception) {
- $allowedRetries = $this->allowedRetries(
- $exception->getCode(),
- $exception->getErrors()
- );
- if (!$this->canAttempt() || !$allowedRetries) {
- throw $exception;
- }
- if ($allowedRetries > 0) {
- $this->maxAttempts = min(
- $this->maxAttempts,
- $this->attempts + $allowedRetries
- );
- }
- }
- }
- }
- /**
- * Runs a task once, if possible. This is useful for bypassing the `run()`
- * loop.
- *
- * NOTE: If this is not the first attempt, this function will sleep in
- * accordance to the backoff configurations before running the task.
- *
- * @return boolean
- */
- public function attempt()
- {
- if (!$this->canAttempt()) {
- return false;
- }
- if ($this->attempts > 0) {
- $this->backOff();
- }
- $this->attempts++;
- return true;
- }
- /**
- * Sleeps in accordance to the backoff configurations.
- */
- private function backOff()
- {
- $delay = $this->getDelay();
- usleep($delay * 1000000);
- }
- /**
- * Gets the delay (in seconds) for the current backoff period.
- *
- * @return float
- */
- private function getDelay()
- {
- $jitter = $this->getJitter();
- $factor = $this->attempts > 1 ? $this->factor + $jitter : 1 + abs($jitter);
- return $this->delay = min($this->maxDelay, $this->delay * $factor);
- }
- /**
- * Gets the current jitter (random number between -$this->jitter and
- * $this->jitter).
- *
- * @return float
- */
- private function getJitter()
- {
- return $this->jitter * 2 * mt_rand() / mt_getrandmax() - $this->jitter;
- }
- /**
- * Gets the number of times the associated task can be retried.
- *
- * NOTE: -1 is returned if the task can be retried indefinitely
- *
- * @return integer
- */
- public function allowedRetries($code, $errors = array())
- {
- if (isset($this->retryMap[$code])) {
- return $this->retryMap[$code];
- }
- if (!empty($errors) && isset($errors[0]['reason']) &&
- isset($this->retryMap[$errors[0]['reason']])) {
- return $this->retryMap[$errors[0]['reason']];
- }
- return 0;
- }
- public function setRetryMap($retryMap)
- {
- $this->retryMap = $retryMap;
- }
- }